Biaryl ketone

A series of fluorinated biaryl ketones (13) was reported by Denmark and coworkers in 1999 and 2002 (Fig. 4) [22, 40]. The introduction of fluorine atoms at the a-position of the reacting carbonyl increased the efficiency of the epoxidation. Fluorinated ketones 13b and 13c displayed high reactivity and good enantioselectivity... 

Scheme 33. OZzgoarylenes [122 c] by Suzuki coupling and synthesis of unsymmetrical (hetero) biaryl ketones by Pd-catalyzed carbonylation [123]...

Interesting applications of the Suzuki coupling protocol are the synthesis of ohgoarylenes with precise length and defined functional groups at both termini of the chain as well as the preparation of unsymmetrical biaryl ketones by the Pd-catalyzed cross-coupling reactions of arylboronic acids with iodoarenes (see Scheme 33). 

In 2009, a one-step protocol for the synthesis of xanthones via Pd-catalyzed coupling between 1,2-dibromoarenes and salicylaldehydes was developed. The success of the reaction relies heavily on the careful selection of a proper palladium catalyst, solvent and base moderate yields of the desired products were formed (Scheme 3.2). In this communication, a reaction mechanism was proposed by the authors. The Pd(0) catalyst first underwent oxidative insertion into one of the carbon-halide bonds to generate the aryl-Pd(ii) intermediate, which reacted with the phenolate to displace the halide, then underwent C-H activation of the C-H bond of the aldehyde to form intermediate A. After abstraction of the hydrogen atom by the base and reductive elimination to exclude the Pd(0) catalyst, the biaryl ketone intermediate was... 

Palladium-catalyzed cross-coupling of benzocyclobutenol 37 and an aryl halide resulted in selective cleavage of the C(sp )-C(sp ) bond to give the biaryl ketone 38 (Scheme 3.17) [27]. 

Co-NHC complexes have been involved in the ortho C-H activation of imines to perform the synthesis of biaryl derivatives. The cross-coupling partner is an aryl chloride activated by neopentylmagnesium bromide. After hydrolysis of the imine, the corresponding biarylic ketones are obtained in moderate to excellent yield. 

Denmark and co-workers used 7-membered C -symmetric carbocyclic biaryl ketones 362 for the asymmetric epoxidation of fraris-olelins [247]. Ketone 362c was found to be more active than ketones 359 (Table 7.25). At the same time the structurally related fluorinated binaphthyl ketones 363 of similar catalytic profile were reported by Behar et al. in 2002 [248]. 

Aryl iodides couple with aryl aldehydes in the presence of NiBr2(dppe) and Zn to give the corresponding biaryl ketones. The use of a bidentate ligand is critical to the success of this catalytic reaction [86]. 

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